Outboard motor apparatus



Oct. 20, 1964 R. DJMATTSON ETAL OUTBOARD MOTOR APPARATUS Filed 001;. 30, 1961 INVENTORS JOHN R. MATT-$0M ROY o. MATTSON ATTORNEY United States Patent This invention relates to new and very useful ultra light-weight, buoyant outboard assemblies for boats.

More particularly, this invention is directed to a novel means for maintaining the conventional components of an outboard motor assembly, to wit, power source, power transmission means, and propeller, in fixed relationskdp to one another without the use of the conventional massive, heavy metallic supporting structures.

Still more particularly, this invention is directed to an ultra lightweight, buoyant outboard motor assembly in which conventional assembly components are maintained in fixed relationship to one another by being embedded within foamed-in-place plastic. By careful selection of components and types of construction, in accordance with the teachings of this invention, one can manufacture a complete outboardmo-tor assembly which has an optimum combination of desirable performancecharacteristics but a minimum total weight.

It is an object of this invention to provide an ultra lightweight, buoyant outboard motor assembly. v It is another object of this invention to provide an ultra light-weight and buoyant meanslfor maintaining in rigid, functional relationship to one another the combined power source, power transmission means, and propeller component combination of an outboard motor assembly employ ing foamed-in-place plastic.

Other objects and advantages of this invention will appear hereinafter as this disclosure progresses, references being had to the accompanying drawings in which:

FIGURE 1 is a prospective exterior view of an outboard motor assembly embodying the principles of the outboard motor assembly of FIG. 1 showing a partial cut away view of the propeller region.

In FIG. 1 is shown the exterior appearance of an outboard motor assembly made in accordance with the teachings of the invention. The power source and power transmission means are housed within a thin exterior shell of plastic or metal,here shown as a plastic shell. The space between this shell and the power source and the power transmission means is filled with a foamed-in-place plastic which is porous and not very dense. Such foamed-inplace plastic holds the outboard motor assembly components in fixed relationship to one anotherl If the foamed-in-place plastic has sufiicient strength characteristics, there is no need to employ an exterior shell of thin plastic or metal. Instead the foamed-inplace plastic itself can serve as the exterior surface of the outboard motor assembly.

In general, the exterior surf-aces of the outboard motor assembly of this invention have a compressive strength of at least about 30 pounds per square inch (p.s.i.), a tensile strength of at least about 50. p.s.i., a fiexural strength of at least about 50 p.s.i., and an impact strength of at least about 1.0 p.s.i., all tests being standard A.S.T.M.

procedures. Preferably, the exterior surface of an outstrength of 400 p.s.i., a tensile strength of 1000 p.s.i., a

, 3,153,397 Patented 0st. .20., 1964 fiexural strength of 1000 p.s.i., and an impact strength of 2.0 psi. It is also preferred that the exterior, as well as the interior, surfaces be substantially insoluble in water and common hydrocarbons and oils of petroleum origin, and that they be substantially unaffected by temperatures below about 100 C; The surfaces should also be resistant to attack by microorganisms.

When the exterior surface is to be a plastic shell, there are a number of different plastics and metals which are suitable. For example, suitable thermoplastics include acetal, acrylic, cellulosic, chlorinated polyether, nylon, polyethylene, polypropylene, polycarbonate, polychlorotrifiuoroethylene, polytetrafiuoroethylene, FEP fluorocarbon, polystyrene complex, vinyl polymers, polyvinylacetate, butyral, chloride, chloride-acetate, vinylidenechloride, vinylformal, rubber molding compounds (chlorinated rubber). The thermoplastic polymers may be reinforced with up to about 70 percent of the following materailsz Glass, mineral, synthetic fiber, asbestos, cellulosic fabric, cotton flock. Examples of suitable thermoset resins for manufacturing the plastic shell include such polymeric material as casein molding compounds, diallylphthalate molding compounds, furan molding compounds, melamineformaldehyde molding compounds, phenol-formaldehyde molding'compounds, furfural molding compounds, polyacrylic ester, polyester and alkyl, silicone, urea- "formaldehyde, epoxy, allyl casting resins, epoxy casting styrenes, the polyvinylchlorides, and the polyisocyanates board motor assembly of this invention has a compressive (he, the polyurethanes). They can be conventionally utilized and reinforced with additives when and if necessary or desirable, in accordance with wishes.

As is now conventionally done, the outboard moto assembly components will be equipped with their usual housings and associated paraphernalia. Thus, an internal combustion engine will have its usual engine block, gas

.tank, etc; a power transmission means using a gear train ciated elements are integral one with another, so that the foamed-inplace surrounding plastic serves only to support and maintain these components in fixed relationship one to another and does not necessarily enter into any functional, operational relationship with assembly components. Without the foanied-in-place plastic, the assembly components even as a whole do not and cannot maintain the necessary fixed relationship to one another for operability.

From a structural support standpoint, the actual shape of the exterior surfaces of supporting structures described in this invention is unimportant, assuming that the in ternal and external surface strength characteristics are as described. However, one will naturally choose assembly components for any given embodiment which permit the fabrication of a supporting structure whose exterior surin use are hydrodyanmically streamlined.

In general, interior surfaces, i.e.','those contacting outboard motor assembly components, of the foamed-inplace plastic should have assocaited with them compressive strengths of at least 30 p.s.i., tensile strengths of at least 50 p.s.i., flexural strengths of at least 50 p.s.i., and impact strengths of at least 1.0 p.s.i. Of course, as those skilled in the art will recognize, the particular strength characteristics best suited for interior surfaces will vary very widely, being largely dependent upon the particular type of motor components involved in any given instance. Consequently, the foregoing figures must be regarded as being generalized values which can change somewhat according to the particular embodiment involved.

From the foregoing description, it can be seen that when the foamed-in-plastic used in any given embodiment has both the internal and external surface strength requirements indicated, no reinforcing means augmenting .foam strength characteristics need be empolyed. However, when a given foams strength, interiorly or exteriorly, is deficient, it can (depending on individual circumstances) be built up either by additive addition to the foam matrix or by a shell arrangement, such as the exterior shell'described above.

Broadly, one always selects a plastic for 'foaming-inplace which has a specific gravity after processing of less than one, independent of the actual density. This assures that the resulting outboard motor assembly will be ultra.

light-Weight and buoyant. 7

Now the term buoyant as used herein has reference to the fact that outboard motor assemblies made in accordance with this invention have the associated characteristic that they generally have a lower specific gravity, usually greatly less, than that associated with the outboard motor assembly components themselves apart from and independent of the supporting structure for the assemd -5 combination of power'source, flexible drive shaft and propeller, for purposes of this invention.

Attention should be directed to the water intake arrangement shown in FIG.'4. A scoop is shown through which intake of water can occur, such water intake can either be derived fromthe passage of the outboard motor through the water, or it can be achieved by the use of a small pump arrangement within either the propeller or the power source regionf'of the outboard motor assembly. The plastic or metal shell can be made either as a single piece or two separate halves or any other means convenient to the invention.

To accomplish foaming-in-place, any convenient method known to the art can be employed. Thus, for example, an internal engine, flexible drive shaft, and propeller arrangement can first be positioned in a mold and then bly. Preferably, a complete outboardmotor assembly in which the components are maintained in fixed relationshipwith each other in accordance with this invention is so buoyant that it will float, that is, the entire assembly has a specific gravity of lessthan one.

Usually the entire assembly is so buoyant that even if it does not float, its specific gravity is so near to unity that only slight additional supplement-a1 means is necessary to cause the entire outboard motor assembly to float.

In FIG. 1 positioned on the exterior surface of shell 10 is a conventional mounting bracket 11. Propeller 12 is conventionally mounted in the base of the assembly, and the flexible shaft 13'drive means is secured to the power source at the top of the outboard motor assembly.

In FIG. 2 is shown a preferred relationship between interior parts of a motor assembly. Within the interior of the foam 17 is a flexible drive shaft 13' and exhaust tube 14. As shown, the drive shaft 13 is enclosed and shielded by a casing 22. In order to keep the temperature of the exhaust tube 14 below a temperature that would adversely affect the foamed-plastic encasing material, the exhaust tube 14 is wrapped with. a water-cooling pipe 16. This wraping is particularly tight near the upper .regions of the engine where the temperatures are the 14 can actually run parallel to the exhaust pipe and need not wrap the same. 1

In FIG. 4 is shown the arrangement in the propeller region. foamed-in-place, is employed as a journal for the flexible shaft itself. Genarally a conventional flexible shaft arrangement is employed, except that, as those skilled in the art will appreciate, the shaft and housing used is heavy enough to withstand the vibrational stresses and the rotational velocities and torque involved in any given A conventional bearing arrangement '18, also the plastic foamed-in-place about the components. If necessary or desirable, the mold itself can comprise a shell wall which is to be left associated with the completed assembly.

Any conventional power transmission means can be employed in the devices of this invention, such as flexible cables, rigid shafts, gear trains, etc. Similarly, the propeller shaft can be of any known type. Its associated bearing should be of a type which is conveniently embedded in plastic and yet at the same time has, the necessary mechanical properties. Thus, bushings (metal or plastic), as well as roller or ball bearings can be used. Usually the power source will be an internal combustion engine. Naturally, to produce maximum light weight, the

selection of metals in components must be carefully made.

It is surprising and unexpected that the foam-encased outboard motor assemblies of this invention should produce such great reductions in total assembly weight per unit of rated horsepower without any particular sacrifice of desirable properties. Indeed, outboard motor assemblies of this invention frequently have superior properties to conventional all-metal assemblies. Usually outboard motor assemblies of 'this invention are atleast 20 percent lighter than conventionalcommercial outboard motor assemblies of equivalent rated horsepower, though it is not uncommon for assemblies of this invention to be at least 50 percent or even lower in weight than such conventional assemblies. No metal is needed for supporting a structure of the type described in this invention.

A further valuable feature of the present invention is that the described supporting structures are substantially unaffected by salt water- -a great advantage over conventional metal-supporting structures.

A still further valuable feature is'that the foamed-inplace plastic permits the construction of lower regions in an outboard motor which are flexible. Such flexibility not only. provides resiliency but in the case of extreme flexibility aids in portability and storage of the outboard motor while not in use. I

The claim is:

An outboard motor assembly comprising (a) a power source,

(b) a propeller,

(c) a power transmission mechanism including a flexible shaft drive means extending generally downwardly from said power headto a generally rearwardly extending propeller shaft portion,

(d)' means enclosing and journaling said power transmission mechanism, j

(e) a buoyant body surrounding said means forwardly er the rear end of siad propeller shaft portion,

(f said propeller being secured to the rear end of said propeller shaft portion,

. (g) said buoyant body extending forwardly and upwardly from said propeller to said power source and being cross-sectionally streamlined, and

(h) said buoyant body including a thin, exterior shell shaving a compressive strength of at least about 30 p.s.i. whose interior space between said shell and said power transmission mechanism and said means is filled with a foamed-in-place plastic.

References Cited in the file of this patent UNITED STATES PATENTS Running Sept. 3, 1940 Bosma Feb. 7, 1950 

